Arriving in Sri Lanka during the Eid public holiday, as usual I spotted statues of the Buddha, Hindu deities and Jesus. But I was struck by the numerous, sometimes huge, images of the president. In towns and villages across the south, Mahinda Rajapaksa's moustached face smiled down on passersby.

Perhaps this was an aftereffect of this year's presidential election campaigning, or euphoria in 2009 in much of the island at the end of a long civil war and the lifting of the threat of terrorism. But his apparently iconic status has disturbing implications in the light of recent events.

An amendment to the constitution has been rushed through parliament, giving unprecedented powers to the president.Under the 18th amendment, no longer is he limited to two terms: he can stand for office repeatedly. More importantly, checks and balances against abuse of power have largely been removed. The independence of the commission that oversees elections has been undermined, and the president will have increased control over appointment of top judges and police.

Members of his family now hold several senior government positions, and his eldest son Namal, now an MP, is widely regarded as a potential successor. This impression is promoted by his own website, which proclaims: "A future leader with a friendly spirit, possessing good values is what comes to mind when meeting the dashing and smashing, young Namal Rajapaksa. His credo in life is to bring peace to Sri Lanka starting with the nation's youth, instilling patriotism and universal harmony to bring everyone together."

In the 1980s, democracy and human rights came under attack from the ruling party of the time, bravely opposed by activists such as Mahinda Rajapaksa, then an idealistic opposition MP. But even that government did not go so far in concentrating power in the hands of one person. The situation is unprecedented in post-independence Sri Lanka, except in those parts of the north and east where Velupillai Prabhakaran, the ruthless Tiger leader, once ruled dictatorially, helping to bring misery on large numbers of Tamils until his defeat and death. He was treated as a demi-god, an example that Sri Lankan politicians today would do well to avoid.

While there have been angry protests within Sri Lanka at the undermining of democracy, the main opposition party is in disarray, and many people have not yet woken up to the implications of a measure adopted so speedily.

The president has also had some success in portraying himself as the representative of a nation, so that any questioning of his decisions is regarded as a slur on the people of Sri Lanka – again an approach with unfortunate echoes of that taken by Prabhakaran and other authoritarian leaders throughout the world. All too often, an initial boost to national pride has been followed by ruin, as destructive policies have been pushed through without proper challenge, resulting in disaster.

Treating any politician as a near-deity, and giving him or her absolute power, is a dangerous course. The trade unionists, human rights activists, lawyers and many others in Sri Lanka who are resisting the slide towards dictatorship despite the accusations and threats they face deserve to be listened to, before it is too late.